The invention relates to the field of textile reinforcements for composite materials.
It is now well known to manufacture composite materials of high strength, despite their low weight, by coupling a matrix, generally a heat-curable resin with a set of textile structures, such as tissues. There are various methods for obtaining such materials. Reinforcing tissues can be impregnated with the resin manually, to be subsequently subjected to a contact molding method. A method which is employed, industrially consists of placing the textile reinforcement in a mold into which the resin is introduced and, to facilitate the flow of the latter, creating a pressure gradient in the mold to permit an optimum resin transfer. Another widely employed method consists of compressing a stack of textile reinforcements in a mold into which resin has been introduced.
In yet another method, a resin film or sheet is transferred under the effect of heat and pressure onto a stack of tissues or a multidimensional textile structure with fiber orientation. A further method also consists of passing the reinforcement, after impregnation with a resin, through a heated die to produce continuous profiled articles by extrusion. All these processes for the manufacture of articles made of composite materials are well known to the specialist and therefore do not need to be described in greater detail.
In practice, the cutting, handling and assembling of a number of layers and the forming of dry, that is to say not preimpregnated, textile structures frequently present problems and limit the possibilities of automation of the operations for the manufacture of articles made of composite materials, especially according to the methods referred to above.
In particular, the placing of dry reinforcements on a mold of complex shapes is a problem which has not been properly resolved, most especially in the case of stacking of a number of layers and when attempts are made to conform to the precise fiber orientations and to produce variable thicknesses, in order to obtain high mechanical performances.